Rapid FDTD analysis of shielding enclosures

A numerical methodology is presented for fast broadband analysis of shielding enclosures. The methodology combines the standard finite-difference time-domain (FDTD) method with a non-symmetric Lanczos eigenvalue algorithm to generate directly a Pade approximation of the electromagnetic response of the structure over the frequency range of interest. The numerical implementation is such that each iteration of the Lanczos algorithm is computationally equivalent to the update of the electromagnetic fields in the FDTD algorithm. However, no time stepping is required. Thus, both the time step-imposed numerical stability constraint of the FDTD algorithm and its time step-controlled frequency resolution are relaxed. The proposed methodology generates the continuous response of the system at a fraction of the computational cost required by the FDTD method. The effectiveness of the methodology is demonstrated through several numerical experiments.